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backend.go
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backend.go
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// Package gcs implements remote storage of state on Google Cloud Storage (GCS).
package gcs
import (
"context"
"encoding/base64"
"encoding/json"
"fmt"
"os"
"strings"
"cloud.google.com/go/storage"
"github.com/hashicorp/terraform/backend"
"github.com/hashicorp/terraform/helper/pathorcontents"
"github.com/hashicorp/terraform/helper/schema"
"github.com/hashicorp/terraform/httpclient"
"golang.org/x/oauth2"
"golang.org/x/oauth2/jwt"
"google.golang.org/api/option"
)
// Backend implements "backend".Backend for GCS.
// Input(), Validate() and Configure() are implemented by embedding *schema.Backend.
// State(), DeleteState() and States() are implemented explicitly.
type Backend struct {
*schema.Backend
storageClient *storage.Client
storageContext context.Context
bucketName string
prefix string
defaultStateFile string
encryptionKey []byte
}
func New() backend.Backend {
b := &Backend{}
b.Backend = &schema.Backend{
ConfigureFunc: b.configure,
Schema: map[string]*schema.Schema{
"bucket": {
Type: schema.TypeString,
Required: true,
Description: "The name of the Google Cloud Storage bucket",
},
"path": {
Type: schema.TypeString,
Optional: true,
Description: "Path of the default state file",
Deprecated: "Use the \"prefix\" option instead",
},
"prefix": {
Type: schema.TypeString,
Optional: true,
Description: "The directory where state files will be saved inside the bucket",
},
"credentials": {
Type: schema.TypeString,
Optional: true,
Description: "Google Cloud JSON Account Key",
Default: "",
},
"access_token": {
Type: schema.TypeString,
Optional: true,
DefaultFunc: schema.MultiEnvDefaultFunc([]string{
"GOOGLE_OAUTH_ACCESS_TOKEN",
}, nil),
Description: "An OAuth2 token used for GCP authentication",
},
"encryption_key": {
Type: schema.TypeString,
Optional: true,
Description: "A 32 byte base64 encoded 'customer supplied encryption key' used to encrypt all state.",
Default: "",
},
"project": {
Type: schema.TypeString,
Optional: true,
Description: "Google Cloud Project ID",
Default: "",
Removed: "Please remove this attribute. It is not used since the backend no longer creates the bucket if it does not yet exist.",
},
"region": {
Type: schema.TypeString,
Optional: true,
Description: "Region / location in which to create the bucket",
Default: "",
Removed: "Please remove this attribute. It is not used since the backend no longer creates the bucket if it does not yet exist.",
},
},
}
return b
}
func (b *Backend) configure(ctx context.Context) error {
if b.storageClient != nil {
return nil
}
// ctx is a background context with the backend config added.
// Since no context is passed to remoteClient.Get(), .Lock(), etc. but
// one is required for calling the GCP API, we're holding on to this
// context here and re-use it later.
b.storageContext = ctx
data := schema.FromContextBackendConfig(b.storageContext)
b.bucketName = data.Get("bucket").(string)
b.prefix = strings.TrimLeft(data.Get("prefix").(string), "/")
if b.prefix != "" && !strings.HasSuffix(b.prefix, "/") {
b.prefix = b.prefix + "/"
}
b.defaultStateFile = strings.TrimLeft(data.Get("path").(string), "/")
var opts []option.ClientOption
// Add credential source
var creds string
var tokenSource oauth2.TokenSource
if v, ok := data.GetOk("access_token"); ok {
tokenSource = oauth2.StaticTokenSource(&oauth2.Token{
AccessToken: v.(string),
})
} else if v, ok := data.GetOk("credentials"); ok {
creds = v.(string)
} else if v := os.Getenv("GOOGLE_BACKEND_CREDENTIALS"); v != "" {
creds = v
} else {
creds = os.Getenv("GOOGLE_CREDENTIALS")
}
if tokenSource != nil {
opts = append(opts, option.WithTokenSource(tokenSource))
} else if creds != "" {
var account accountFile
// to mirror how the provider works, we accept the file path or the contents
contents, _, err := pathorcontents.Read(creds)
if err != nil {
return fmt.Errorf("Error loading credentials: %s", err)
}
if err := json.Unmarshal([]byte(contents), &account); err != nil {
return fmt.Errorf("Error parsing credentials '%s': %s", contents, err)
}
conf := jwt.Config{
Email: account.ClientEmail,
PrivateKey: []byte(account.PrivateKey),
Scopes: []string{storage.ScopeReadWrite},
TokenURL: "https://oauth2.googleapis.com/token",
}
opts = append(opts, option.WithHTTPClient(conf.Client(ctx)))
} else {
opts = append(opts, option.WithScopes(storage.ScopeReadWrite))
}
opts = append(opts, option.WithUserAgent(httpclient.UserAgentString()))
client, err := storage.NewClient(b.storageContext, opts...)
if err != nil {
return fmt.Errorf("storage.NewClient() failed: %v", err)
}
b.storageClient = client
key := data.Get("encryption_key").(string)
if key == "" {
key = os.Getenv("GOOGLE_ENCRYPTION_KEY")
}
if key != "" {
kc, _, err := pathorcontents.Read(key)
if err != nil {
return fmt.Errorf("Error loading encryption key: %s", err)
}
// The GCS client expects a customer supplied encryption key to be
// passed in as a 32 byte long byte slice. The byte slice is base64
// encoded before being passed to the API. We take a base64 encoded key
// to remain consistent with the GCS docs.
// https://cloud.google.com/storage/docs/encryption#customer-supplied
// https://github.com/GoogleCloudPlatform/google-cloud-go/blob/def681/storage/storage.go#L1181
k, err := base64.StdEncoding.DecodeString(kc)
if err != nil {
return fmt.Errorf("Error decoding encryption key: %s", err)
}
b.encryptionKey = k
}
return nil
}
// accountFile represents the structure of the account file JSON file.
type accountFile struct {
PrivateKeyId string `json:"private_key_id"`
PrivateKey string `json:"private_key"`
ClientEmail string `json:"client_email"`
ClientId string `json:"client_id"`
}